This invention is related to a simple, new and useful method whereby some or all of a specific indoor pollutant can be removed.
Conventional methods usually involve the adsorption of such pollutants onto activated surfaces such as charcoal, silica gel, alumina or other meterials with large surface areas, (see R. E. Goddard & J. A. Coles, Canadian Pat. #626,216 and J. W. Kasmark Jr., M. L. Dooley & A. H. Jones, U.S. Pat. #4,227,904).
Another conventional method is to use a solution to react with the specific gas, (see M. A. Kise, Canadian Pat. #643,062).
Such methods are usually non-specific and quite expensive to produce and operate. In the case where aqueous solutions are used the air becomes saturated with water and higher humidity levels result. In the case of adsoprtion systems, the pollutant, usually present in trace quantities, must compete with oxygen, nitrogen, carbon dioxide and water in the air in order to be adsorbed to a significicant extent. The adsorption is also temperature dependent and not always complete as far as the pollutant is concerned.
Though Gaylord (U.S. #4,374,814) has described a reactive coating to remove formaldehyde, his polyhydric water-soluble polymers requires moisture as well as an acidic or basic catalyst to effect reaction between formaldehyde and the coated polymer. Furthermore, the reduction of formaldehyde by Gaylord is far from complete and residual levels are in excess of the accepted TLV level of 0.1 ppm.
Gesser (U.S. #4,547,350) has shown that polymeric amines and hydrazines can trap formaldehyde efficiently. However, the coating through effective for one week ceased to remove formaldehyde from air soon after that due to the surface coating formed by reaction and the inability of this layer to exchange with the bulk unreacted amine in the film. Thus a very small fraction of the amine in the film is actually effective and consumed by reaction. This invention describes a method whereby the concentration of aldehyde and in particular formaldehyde can be reduced to levels far below the Toxic level (TLV=0.10 ppm), and where the concentration of H.sub.2 S can be reduced to such small concentrations so as to be no longer present as an odor problem (i.e. [H.sub.2 S].perspectiveto.0.01 ppm).